Indirect or direct fired heater

ABSTRACT

A SELECTIVELY INDIRECT AND DIRECT-FIRED AIR HEATER HAS A FIRE TUBE AND SHEEL SECTION, A BLOWER SECTION DETACHABLY CONNECTED TO THE FIRE TUBE AND SHELL SECTION AND ARRANGED FOR MOVING AIR THERETHROUGH, AND A PLURALITY OF HEATING UNITS SELECTIVELY CONNECTIBLE TO THE FIRE TUBE AND SHELL SECTION FOR PASSING COMBUSTION GASES TO A FIRE TUBE THEREOF. EACH HEATING UNIT IS DESIGNED TO BURN A DIFFERENT TYPE OF FUEL. THE FIRE TUBE AND SHELL SECTION HAS A HOUSING PROVIDED WITH A WALL DEFINING THE FIRE TUBE. A SHELL IS ARRANGED IN HEAT EXCHANGE RELATION WITH RESPECT TO THE HOUSING, AND IS PROVIDED WITH A WALL ARRANGED AROUND THE HOUSING WALL AND DEFINING A FLUID OR AIRFLOW PASSAGE HAVING INLET AND OUTLET OPENINGS. THE FIRE TUBE HAS AN OUTLET OPENING HAVING A FLANGED DUCT SURROUNDING SAME. A PIPE IN COMMUNICATION WITH THE SHELL INLET OPENING IS PROVIDED WITH A FLANGE WHICH IS SELECTIVELY JOINABLE WITH THE FLANGED DUCT FOR SELECTIVELY CONNECTING THE FIRE TUBE OUTLET OPENING TO THE SHELL INLET OPENING FOR CYCLING COMBUSTION GASES THROUGH THE AIRFLOW PASSAGE. THE FIRING IS DIRECT WHEN THE FIRE TUBE OUTLET IS SO CONNECTED, AND INDIRECT OTHERWISE.   D R A W I N G

United States Patent [1 1 Muckelrath [11] 3,779,230 451 Dec. 18, 1973 11 INDIRECT OR DIRECT FIRED HEATER [75] Inventor: Ernest R. Muckelrath,Tioga, N.

Dak.

H [73] Assignee: Air Heaters, Inc., Tioga, N. Dak.

[22] Filed: Apr. 7, 1972 [21] Appl. No.: 241,998

Primary ExaminerWilliam E. Wayner Assistant Examiner-William E.Tapolcai, .11. AttorneyHarvey B. Jacobson [57] ABSTRACT A selectivelyindirect and direct-fired air heater has a fire tube and sheel section,a blower section detach ably connected to the fire tube and shellsection and arranged for moving air therethrough, and a plurality ofheating units selectively connectible to the fire tube and shell sectionfor passing combustion gases to a fire tube thereof. Each heating unitis designed to burn a different type of fuel. The fire tube and shellsection has a housing provided with a wall defining the fire tube. Ashell is arranged in heat exchange relation with respect to the housing,and is provided with a wall arranged around the housing wall anddefining a fluid or airflow passage having inlet and outlet openings.The fire tube has an outlet opening having a flanged duct surroundingsame. A pipe in communication with the shell inlet opening is providedwith a flange which is selectively joinable with the flanged duct forselectively connecting the fire tube outlet opening to the shell inletopening for cycling combustion gases through the airflow passage. Thefiring is direct when the fire tube outlet is so connected, and indirectotherwise.

11 Claims, 2 Drawing Figures l INDIRECT OR DIRECT FIREDIIEATERBACKGROUND OF THE INVENTION l. Field of the Invention This inventionrelates generally to a fluid heater, particularly an air heater, andspecifically to such a heater which may be selectively arranged inindirect and direct fired heating modes and burn different type fuels.

2. Description of the Prior Art Heaters are known which put out a largevolume of constant temperature heated air for heating exterior workareas such as encountered in construction and the like. These heatersenable work to be performed even under extremely cold weatherconditions.

These heaters are basically classified as indirect and direct-fired, andby the type of fuel burned. U. S. Pat. No. 3,388,697 discloses anexample of an indirect-fired heater. By indirect-fired is meant that theair being heated is not contacted directly by the combustion gasesheating same.

The prior art air heaters are basically designed and constructed aseither an indirect or direct-fired heater, and are further intended toburn only a designated type of fuel, which is usually either a fuel oilor gas.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an air heater capable of a high heat output and that may beselectively arranged in either an indirect or a directfired mode.

It is a further object of the present invention to provide an air heaterwhich is capable of being set up to burn selectively any suitable, knownfuel.

These and other objects are achieved according to the present inventionby providing a selectively indirect and direct-fired fluid heater havinga housing provided with a wall defining a fire tube having an inlet andan outlet for permitting combustion gases to pass through the fire tube.A shell is provided having a wall arranged in heat exchange relationwith respect to the housing wall so as to define a flu'id flow passagehaving inlet and outlet openings. Means are mounted on the housing andshell for selectively connecting the fire tube outlet opening to theshell inlet opening for cycling combustion gases through the fluid flowpassage. The firing being in the direct-fired mode when the fire tubeoutlet is so connected, and in the indirect-fired mode otherwise.

In a preferred embodiment of the present invention, the selectivelyconnecting means has a duct mounted on the housing wall surrounding theoutlet opening thereof. This duct extends through a hole provided in theshell wall, and is provided with a flange on an end thereof spaced fromthe housing wall. An additional flange is mounted on the shell wallsurrounding the inlet opening thereof. The selectively connecting meansfurther has a pipe having at an end thereof an elbow provided with aflange which joins with the flange mounted on the shell wall. The pipeis also provided with a flange which is selectively joinable with theduct flange for creating the direct-fired mode.

In an advantageous feature of the present invention, the fire tube andshell form a fire tube and shell section. A blower section is detachablyconnected to the fire tube and shell section, and is arranged for movingfluid therethrough. A plurality of heating units are provided.

Each heating unit is designed to burn a different type fuel, and isselectively connectible to the fire tube and shell section for passingcombustion gases to a fire tube of the fire tube and shell section.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic, sideelevational view, partly cut away and in section, showing a heateraccording to the present invention arranged in an indirect-fired mode.

FIG. 2 is a schematic, side elevational view, partly cut away and insection, similar to FIG. 1 but showing a heater according to the presentinvention arranged in a direct-fired mode.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specificallyto the drawings, a selectively indirect and direct-fired air heater 10according to the present invention has a fire tube and shell section 12.A blower section 14, which may be a conventional scroll-type centrifugalblower as illustrated, is detachably connected to section 12, and isarranged for moving air therethrough.

A plurality of heating units 16 (FIG. 1) and 18 (FIG. 2) are provided.Each unit I6, 18 has a burner 17, 19, respectively, designed to burn adifferent type fuel, and to be selectively connectible to section 12 forpassing combustion gases to the fire tube thereof. Each burner 17, 19 isarranged in an enclosure 20, which may also enclose the controls (notshown) for the particular unit 16, 18. Burners 17, 19 and the controlstherefor are of a conventional nature, and, therefore, they will not bediscussed in detail herein. Unit 16 may be, for example, a fuel oilburning unit, and receive its fuel from a fuel oil tank 22 (FIG. 1).Unit 18 may be, for example, a gas burning unit, and receive a liquefiedgas such as propane from one or more liquefied gas bottles (not shown)placed in a, for example, liquefied gas bottle enclosure 24 (FIG. 2).

Section 12 of heater 10 further has a base member 26 connected theretofor supporting same. In a similar manner, sections 14 and 16 have basemembers 28 and 30, respectively. These base members 26, 28, and 30 haveinterfingering portions with mating holes running transversely throughthem for receiving pins 32 for detachably attaching section 14 and oneof units 16, 18 to section 12 to form a heater 10. Further thisconstruction permits heater 10 to be disassembled into three sectionsfor easier shipment.

Section 12 of heater 10 has a housing 34 provided with a substantiallycylindrical wall 36 defining a tire tube having an inlet opening 38 andan outlet opening 40 for permitting combustion gases from the burner 17,19 of heating unit 16, 18 to pass through the fire tube. Wall 36 may beconstructed from, for example, a stainless steel. A shell 42 is providedwith a substantially cylindrical wall 44 arranged around wall 36. Walls36 and 44 define a substantially annular fluid flow passage having aninlet opening 46 and an outlet opening 48. Advantageously, a cone-shapeddiffuser 49 is connected to outlet opening 48 to lead the heated airinto blower section 14.

As is clearly shown in the drawings, housing 34 and shell 42 arearranged coaxially, outlet opening 38 and inlet opening 46 are arrangedin a respective wall 36, 44 co-directionally from the common axis ofhousing 34 and shell 42, and lie in a common radial plane. The end ofhousing 34 adjacent outlet opening 40 is covered by a plate 50, and theend of shell 42 adjacent inlet opening 46 has a cover 51 arrangedthereon and provided with inlet opening 38.

A means mounted on housing 34 and shell 42 for selectively connectingoutlet opening 40 to inlet opening 46 for cycling combustion gasesthrough the fluid flow passage will now be described. A duct 52 ismounted on wall 36 surrounding outlet opening 40. This duct 52 extendsthrough a hole 54 provided in wall 44, and is provided with a flange 56on the end thereof spaced from wall 36. A flange 58 is mounted on wall44 and arranged surrounding inlet opening 46.

A pipe 60 is provided for bringing air into the annular fluid flowpassage. This pipe 60 has at an end thereof an elbow 62 provided with aflange 64 which joins with flange 58 to form a flange coupling. Pipe 60is also provided with a flange 66 at a point thereon spaced from flange64 the same distance as flange 58 is spaced from flange 56. Flange 66 isselectively joinable with flange 56, as shown in FIG. 2 of the drawings,for cycling combustion gases through the fluid flow-passage and creatinga direct-fired mode. When heater is arranged in the indirect-fired mode,as shown in FIG. 1 of the drawings, a plate 68 may be arranged on flange66 in a known manner for covering same.

When heater 10 is arranged in the indirect-fired mode (FIG. 1) a stack70 may be arranged on flange 56 in a known manner for carrying away thecombustion gases.

The flow of the air and the combustion gases is desig nated in thedrawings by the flow arrows. With a heater 10 according to the presentinvention, a heating unit can be set up from a standard set ofcomponents which is optimum for a particular location and easily movablethereto. A heating unit 16, 18 may be selected that burns a fuel that ismost desirable for a particular heating situation. Blower-section 14will draw air through pipe 60 and the fluid flow passage to be firedeither indirectly or directly and heated by combustion gases from theheating unit. If contamination of the air by the combustion gases ispermissible, the direct-fired mode shown in FIG. 2 of the drawings maybe employed with a resulting increase in efficiency of operation of theheater 10.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. A selectively indirect and direct-fired fluid heater, comprising, incombination:

a. a housing provided with a wall defining a fire tube having an inletopening and an outlet opening for permitting combustion gases from aburner means to pass through the fire tube;

b. a shell provided with a wall arranged in heat exchange relation withrespect to the housing wall and defining therewith a fluid flow passagehaving inlet and outlet openings; and

c. means for arranging the heater in one of a direct firing mode and anindirect firing mode, and including means mounted on said housing andshell for selectively connecting the fire tube outlet opening to theshell inlet opening and cycling combustion gases through the fluid flowpassage and arranging the heater in the direct firing mode, the heaterbeing arranged in the indirect firing mode when the firing tube outletopening is disconnected from the shell inlet openings.

2. A structure as defined in claim 1, further including base meansconnected to said shell for supporting same, and means provided on saidbase means for selectively attaching heating units burning differenttype fuels to the base means, and arranging the heating units forpassing combustion gases through the fire tube inlet opening.

3. A structure as defined in claim 2, wherein said base means is furtherprovided with means for detachably attaching a blower unit to the basemeans for moving heated fluid through the shell outlet opening.

4. A structure as defined in claim 3, wherein said housing and shell aresubstantially cylindrical and are arranged coaxially, with the fluidflow passage being annular and the fire tube outlet opening and theshell inlet opening arranged in a respective wall codirectionally fromthe common axis of said housing and shell and in a common radial plane,an end of the housing adjacent the tire tube outlet opening beingcovered and an end of the shell adjacent the shell inlet opening havinga cover provided with the fire tube inlet opening.

5. A structure as defined in claim 4, wherein the means for arrangingincludes a duct mounted on the housing wall and surrounding the outletopening thereof, said duct extending through a hole provided in theshell wall and being provided with a flange on an end thereof spacedfrom the housing wall.

6. A structure as defined in claim 5, wherein a flange is mounted on theshell wall surrounding the inlet opening thereof, and the selectivelyconnecting means further includes a pipe having at an end thereof anelbow provided with a flange joined with the flange mounted on the shellwall, said pipe also provided with a flange which is selectivelyjoinable wih the duct flange for creating a direct-fired mode.

7. A structure as defined in claim 1, wherein said housing and shell aresubstantially cylindrical, with the fluid flow passage being annular andthe fire tube outlet opening and the shell inlet opening arranged in arespective wall co-directionally from the common axis of said housingand shell and in a common radial plane, an end of the housing adjacentthe fire tube outlet opening being covered and an end of the shelladjacent the shell-inlet opening having a cover provided with the firetube inlet opening.

8. A structure as defined in claim 7, wherein the means for arrangingincludes a duct mounted on the housing wall and surrounding the outletopening thereof, said duet extending through a hole provided in theshell wall and being provided with a flange on an end thereof spacedfrom the housing wall.

9. A structure as defined in claim 8, wherein a flange is mounted on theshell wall surrounding the inlet opening thereof, and the selectivelyconnecting means fur ther includes a pipe having at an end thereof anelbow provided with a flange joined with the flange mounted on the shellwall, said pipe also provided with a flange which is selectivelyjoinable with the duct flange for creating a direct-fired mode.

10. A structure as defined in claim 1, wherein the means for arrangingincludes a duct mounted on the housing wall surrounding the outletopening thereof said duct extending through a hole provided in the shellwall and being provided with a flange on an end thereof spaced from thehousing wall.

11. A structure as defined in claim 10, wherein a flange is mounted onthe shell wall surrounding the inlet opening thereof, and theselectively connecting means further includes a pipe having at an endthereof an elbow provided with a flange which joins with the flangemounted on the shell wall, said pipe also provided with a flange whichis selectively joinable with the duct flange for creating a direct-firedmode

